Pulsed power capacitors are being developed as land based and space based weapons. There is an urgent need for a high energy density pulsed power capacitor with an energy density greater than 10 KJ/Kg and the ability to deliver energy in the milliseconds range for electro-magnetic gun applications. The highest energy density of current commercially available capacitors is 1.5 KJ/Kg.
The electrostatic energy which can be stored in any dielectric device is directly proportional to: (1) the effective capacitance of the device, and (2) the square of applied voltage. (1) is controlled by the effective dielectric constant and (2) is limited by the breakdown voltage of the dielectric material used in the device.
Polyvinylidene fluoride (PVDF) has the highest dielectric constant of any commercially available capacitor dielectric. A film of PVDF has a dielectric constant of 11 and a small area breakdown strength of 19 KV/mil. Experimental capacitors with energy densities of 2.5 KJ/Kg have been reported but are not yet commercially available.
In the last 10 years there has been a significant effort to develop new polymer films with higher dielectric constants and higher breakdown strengths than PVDF films.
Cyanoresins have high dielectric constants (.epsilon.&gt;15) and are commercially available as film forming resins. Commercial-grade, high dielectric constant cyanoresins have been available since the late 1960's and have been widely used as a coating material for electroluminescent lamps. However, cyanoresin film has not been produced as a capacitor dielectric due to low electrical breakdown strength .about.2 KV/mil and brittle nature of the material.